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The work of Berezinskii, Kosterlitz and Thouless in the 1970s 1 , 2 revealed exotic phases of matter governed by the topological properties of low-dimensional materials such as thin films of superfluids and superconductors. A hallmark of this phenomenon is the appearance and interaction of vortices and antivortices in an angular degree of freedom—typified by the classical XY model—owing to thermal fluctuations. In the two-dimensional Ising model this angular degree of freedom is absent in the classical case, but with the addition of a transverse field it can emerge from the interplay between frustration and quantum fluctuations. Consequently, a Kosterlitz–Thouless phase transition has been predicted in the quantum system—the two-dimensional transverse-field Ising model—by theory and simulation 3 – 5 . Here we demonstrate a large-scale quantum simulation of this phenomenon in a network of 1,800 in situ programmable superconducting niobium flux qubits whose pairwise couplings are arranged in a fully frustrated square-octagonal lattice. Essential to the critical behaviour, we observe the emergence of a complex order parameter with continuous rotational symmetry, and the onset of quasi-long-range order as the system approaches a critical temperature. We describe and use a simple approach to statistical estimation with an annealing-based quantum processor that performs Monte Carlo sampling in a chain of reverse quantum annealing protocols. Observations are consistent with classical simulations across a range of Hamiltonian parameters. We anticipate that our approach of using a quantum processor as a programmable magnetic lattice will find widespread use in the simulation and development of exotic materials. A large-scale programmable quantum simulation is described, using a D-Wave quantum processor to simulate a two-dimensional magnetic lattice in the vicinity of a topological phase transition.

Avocados are an important economic crop of Hawaii, contributing to approximately 3% of all avocados grown in the United States. To export Hawaii-grown avocados, growers must follow strict United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) regulations. Currently, only the Sharwil variety can be exported relying on a systems approach, which allows fruit to be exported without quarantine treatment; treatments that can negatively impact the quality of avocados. However, for the systems approach to be applied, Hawaii avocado growers must positively identify the avocados variety as Sharwil with APHIS prior to export. Currently, variety identification relies on physical characteristics, which can be erroneous and subjective, and has been disputed by growers. Once the fruit is harvested, variety identification is difficult. While molecular markers can be used through DNA extraction from the skin, the process leaves the fruit unmarketable. This study evaluated the feasibility of using near-infrared spectroscopy to non-destructively discriminate between different Hawaii-grown avocado varieties, such as Sharwil, Beshore, and Yamagata, Nishikawa, and Greengold, and to positively identify Sharwil from the other varieties mentioned above. The classifiers built using a bench-top system achieved 95% total classification rates for both discriminating the varieties from one another and positively identifying Sharwil while the classifier built using a handheld spectrometer achieved 96% and 96.7% total classification rates for discriminating the varieties from one another and positively identifying Sharwil, respectively. Results from chemometric methods and chemical analysis suggested that water and lipid were key contributors to the performance of classifiers. The positive results demonstrate the feasibility of NIR spectroscopy for discriminating different avocado varieties as well as authenticating Sharwil. To develop robust and stable models for the growers, distributors, and regulators in Hawaii, more varieties and additional seasons should continue to be added.

Radioisotope irradiators (using cesium-137 or cobalt-60) are used as sources of ionizing radiation to control quarantine or phytosanitary insect pests in internationally traded fresh commodities and to sterilize insects used in sterile insect release programs. There are institutional initiatives to replace isotopic irradiators (producing γ-rays) with lower-energy X-ray machines due to concerns about radiological terrorism and increasingly stringent regulations on the movement of radioisotopes. Questions remain about whether the biological effects of low-energy X-rays are comparable to those of γ-rays since differences in energy levels and dose rates of X-rays may have different efficacies. We compared adult emergence, flight ability, and adult survival in the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritdae), after irradiation of third instar larvae with 100 kV or 5 MeV (5,000 kV) X-rays at 20 and 40 Gy in replicated studies. At 20 Gy, the adult emergence rate was significantly lower after irradiation with 100 kV compared to 5 MeV X-rays, suggesting higher efficacy at the lower energy level. In a follow-up study using 100 kV X-rays, applying 20 Gy using a slow dose rate (0.24 Gy min–1) resulted in significantly higher adult emergence than did a fast dose rate (3.3 Gy min–1), suggesting lower efficacy. Although our study suggests higher efficacy of low energy 100 kV X-rays, there is uncertainty in measuring the dose from an X-ray tube operating at 100 kV using an ionization chamber; we discuss how this uncertainty may change the interpretation of the results. Using a 100 kV X-ray irradiator to develop a phytosanitary treatment may underestimate the dose required for insect control using commercial high-energy γ-ray or X-ray systems.

The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

Abstract Behavioral differences between related insects may inform how pest management strategies or conservation efforts are tailored to specific species. Movement behavior is particularly important, but few studies have undertaken head-to-head comparisons to evaluate differences in interspecific movement. This study used harmonic radar to simultaneously track 2 agriculturally important tephritid fruit fly species, Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann), in an outdoor cage (experiment 1) and a coffee field (experiments 2 and 3) to assess fly directional movement, distance, and speed parameters. In general, both fly species have similar movement parameters. However, experiment 2 showed B. dorsalis to be more active with fewer induced movements and less time needed to record the target number of movement steps. This was supported by a laboratory bioassay (experiment 4) that confirmed B. dorsalis were more active. Mean step-distances only differed in experiment 2 and were longer for C. capitata. Experiment 3 tracked tagged flies over time with 2 B. dorsalis located after 3 d post-release while no C. capitata were located after 48 h. Both species generally move with the prevailing wind. While this study found some differences in movement behaviors between these 2 fly pests, fly movement parameters were more similar than expected, suggesting that it may be possible to characterize the movement of key insect species and then generalize these findings to related taxa. If this is possible, control and detection strategies optimized with movement data from one species may be transferable to other pests, thereby increasing the impact of movement research. Graphical abstract Graphical Abstract

Tracking tagged individuals is an emerging tool to locate invasive wasp nesting sites. Both tag size and transmitter/transceiver cost can limit the applicability of these technologies for eradication measures. This pilot study used a combination of lightweight, inexpensive harmonic radar tags fabricated with superelastic nitinol wire, and off-the-shelf transceivers designed for backcountry rescue. Larger tags weighing 10 mg ( 14 mg with adhesive) were used to track three vespid wasps, Delta esuriens (F), Polistes aurifer Saussure, and Vespula pensylvanica (Saussure), while smaller tags 5 mg ( 8 mg with adhesive) were used only with V. pensylvanica. Wasps were successfully tagged in both laboratory and field settings. Tagged P aurifer were shown to be flight capable in a large outdoor field cage. Subsequently, wasps were tracked in a macadamia nut field (D. esuriens and P aurifer), a coastal habitat (D. esuriens), and in Hawai'i Volcanoes National Park (V. pensylvanica). Flight paths up to 6 steps (maximum 126.7 m) were recorded for D. esuriens (maximum single flight 76.6 m). Vespula pensylvanica were tracked to one nest; several other attempts failed to identify a nest location but did demonstrate the practicality and limitations of following wasps through dense vegetation. Additionally, we demonstrated that V. pensylvanica would carry off tags embedded in small pieces of meat although this technique did not lead to the discovery of any nests. This study demonstrates the feasibility of using an inexpensive method to track wasps, potentially allowing for a rapid and simplified method of locating invasive wasp nests.

Tracking tagged individuals is an emerging tool to locate invasive wasp nesting sites. Both tag size and transmitter/transceiver cost can limit the applicability of these technologies for eradication measures. This pilot study used a combination of lightweight, inexpensive harmonic radar tags fabricated with superelastic nitinol wire, and off-the-shelf transceivers designed for backcountry rescue. Larger tags weighing ~10 mg (~14 mg with adhesive) were used to track three vespid wasps, Delta esuriens (F.), Polistes aurifer Saussure, and Vespula pensylvanica (Saussure), while smaller tags ~5 mg (~8 mg with adhesive) were used only with V. pensylvanica. Wasps were successfully tagged in both laboratory and field settings. Tagged P. aurifer were shown to be flight capable in a large outdoor field cage. Subsequently, wasps were tracked in a macadamia nut field (D. esuriens and P. aurifer), a coastal habitat (D. esuriens), and in Hawaiʻi Volcanoes National Park (V. pensylvanica). Flight paths up to 6 steps (maximum 126.7 m) were recorded for D. esuriens (maximum single flight 76.6 m). Vespula pensylvanica were tracked to one nest; several other attempts failed to identify a nest location but did demonstrate the practicality and limitations of following wasps through dense vegetation. Additionally, we demonstrated that V. pensylvanica would carry off tags embedded in small pieces of meat although this technique did not lead to the discovery of any nests. This study demonstrates the feasibility of using an inexpensive method to track wasps, potentially allowing for a rapid and simplified method of locating invasive wasp nests.

The promise of quantum computing lies in harnessing programmable quantum devices for practical applications such as efficient simulation of quantum materials and condensed matter systems. One important task is the simulation of geometrically frustrated magnets in which topological phenomena can emerge from competition between quantum and thermal fluctuations. Here we report on experimental observations of relaxation in such simulations, measured on up to 1440 qubits with microsecond resolution. By initializing the system in a state with topological obstruction, we observe quantum annealing (QA) relaxation timescales in excess of one microsecond. Measurements indicate a dynamical advantage in the quantum simulation over the classical approach of path-integral Monte Carlo (PIMC) fixed-Hamiltonian relaxation with multiqubit cluster updates. The advantage increases with both system size and inverse temperature, exceeding a million-fold speedup over a CPU. This is an important piece of experimental evidence that in general, PIMC does not mimic QA dynamics for stoquastic Hamiltonians. The observed scaling advantage, for simulation of frustrated magnetism in quantum condensed matter, demonstrates that near-term quantum devices can be used to accelerate computational tasks of practical relevance.